As the need for miniaturization of electronic circuits continues to increase, the need to minimize various circuit elements, such as inductors, increases apace. Inductors are an important component in many discrete element circuits, such as impedance-matching circuits, linear filters, and various power circuits. Since traditional inductors are bulky components, successful miniaturization of inductors presents a challenging engineering problem.
One approach to miniaturizing an inductor is to use standard integrated circuit building blocks, such as resistors, capacitors, and active circuitry, such as operational amplifiers, to design an active inductor that simulates the electrical properties of a discrete inductor. Active inductors can be designed to have a high inductance and a high Q factor, but inductors fabricated using these designs consume a great deal of power and generate noise. Another approach is to fabricate a spiral-type inductor using conventional integrated circuit processes. Unfortunately, spiral inductors in a single level (e.g., plane) occupy a large surface area, such that the fabrication of a spiral inductor with high inductance can be cost- and size-prohibitive. Accordingly, there is a need for other approaches to the miniaturization of inductive elements in semiconductor devices.